464 THE VOYAGE OF H.M.S. CHALLENGER. 



the southward, and the temperature of the surface water was 69°. At 2 p.m. the trawl 

 was hove up and the dredge put over, another sounding being obtained in 400 fathoms 

 (Station 164c, see Sheet 26). The difference in position between this sounding and 

 that of 410 fathoms is due partly to the drift of the ship whilst trawling, owing to the 

 southerly current. At Station 164c there was very little current, and the tempera- 

 ture of the surface water fell to 67°. Serial observations showed that this temperature 

 extended to the depth of 40 fathoms, after which a gradual decrease took place to the 

 bottom. At 5 p.m. the dredge was hove up, and sail was made to the northward under 

 double-reefed topsails and courses. At 6 p.m. the temperature of the surface water again 

 rose to 69 0, 7, .and continued above 69° during the night. 



On the 14th June, at 6.15 a.m., the ship's position was ascertained by observations 

 of a Andromedae and a Aquilse, showing a current of 25 miles in a S. 17° E. direction 

 (true) since 6 p.m. yesterday, or 2 miles per hour. After altering the course to get 

 into a convenient position for sounding, the temperature of the surface water fell to 67° 

 at 10 a.m. At 11 a.m. a sounding was obtained in 2100 fathoms at Station 164d (see 

 Sheet 26), and here no current was experienced. At noon sail was made to triple-reefed 

 topsails, and a course shaped to the eastward. A fresh southwesterly gale prevented 

 temperatures being obtained. 



The Challenger observations on the current off Sydney, New South Wales, showed 

 that in June 1874 the surface temperature, which was 62° in Port Jackson, and 

 66°'5 just outside the heads, rose to 69° at a distance of 20 miles from the land, 

 and continued at, or above, that temperature for 30 miles, when it again fell, at 50 

 miles from the shore, to 67°, and gradually decreased to 63°. When the temperature of 

 the surface water was at, or above, 69°, it was found both by astronomical observations 

 and from observations whilst sounding, that the current was running to the southward at 

 an average rate of 1^ miles per hour ; but directly the temperature of the surface fell to 

 67°, little, if any, current was experienced. The highest temperature registered in the 

 heart of the stream was 70°7. The impossibility of mooring a boat by the dredge or 

 trawl rope, in order to obtain a good observation of the speed of the current in the 

 centre of the stream, was much regretted, but the weather was very unfavourable, there 

 being strong breezes with a considerable swell, so that the rate could only be estimated 

 whilst sounding, and calculated from the differences between the position of the ship by 

 D.R. and observation. In April, when steaming along the land from Montague Island to 

 Sydney, the stream was found close in shore (from Jervis Bay to Port Jackson) ; in June, 

 after a continuance of westerly winds, its inner edge was 20 miles from the coast. 

 This seems to indicate that the wind has much to do with the distance of this stream 

 from the shore. The temperature of the stream in April was 72°, and in June 69°, 

 showing a diminution of 3°. The mean temperature of the air at Sydney in April 

 is 65°, and in June 54 0, 6. 



